One previous design for a balanced vibration exciter suitable for embedding within an acoustic panel radiator uses a pair of disc magnets coupled with poles opposing via a plate of magnetically permeable material such as mild steel. The result is a strong radial field enveloped around the plate which acts on a coil coupled to the radiating element. Of balanced design this exciter may be embedded symmetrically within the panel radiator and the coupling may be arranged so that both sides of the panel are equally coupled.
Alternatively, it is known to employ a cup type of exciter placed on one side or skin of the acoustic panel and this relies on good mechanical coupling through the panel to ensure equal or near equal acoustic output from both sides of the panel.
Two difficulties arise with the radial field type of exciter in specific applications. If high acoustic power is required the electrical input must be raised. This brings consideration of the thermal power in the exciter coil and the means for safely dissipating the excess heat.
Some gain in thermal dissipation can be achieved by using a thermally conductive carrier for the coil, coupled to global, or locally thermally conductive skins. Thus the heat within the panel is conducted outside and is radiated away.